1. Field of the Invention
The present invention relates generally to a disk cartridge with a write protect mechanism which prevents data stored on a disk from being erroneously erased from the disk and prevents new data from being erroneously written on the disk. More specifically, the invention relates to a disk cartridge with such a write protect mechanism, which allows a manually operable switching member of the write protect mechanism to be mounted into a cassette casing smoothly and easily from the outside after the cassette casing has been assembled.
2. Description of the Background Art
A disk cartridge with a write protect mechanism is known as shown, for example, in FIGS. 6 and 7. In FIGS. 6 and 7, a disk cartridge 100 includes a cassette casing 101 which is assembled by welding peripheral edges of an upper half 102 and a lower half 103. Though the upper half 102 is actually a lower half and the lower half 103 is actually an upper half due to FIG. 6 being a perspective view from a bottom side of the disk cartridge 100, directions of "upper, lower, right and left" will be used all through the specification according to the accompanying drawings. The cassette casing 101 includes a disk housing space 104 defined by the inner walls thereof, i.e. between the upper and lower halves 102 and 103, for rotatably housing a magnetic disk 105 therein.
A housing space 106 is further provided in the cassette casing 101 at its rear-right corner outward of the disk housing space 104 for receiving a manually operable switching member 107 of the write protect mechanism. The switching member 107 is slidable between a forward position as indicated in dotted lines in FIG. 7 where the switching member 107 blocks an opening 108 formed in the lower half 103 to prevent a detecting rod of a disk drive unit (not shown) from entering into the housing space 106 via the opening 108 so that the write protect is performed, and a backward position as indicated in solid lines in FIGS. 6 and 7 where the switching member 107 releases the opening 108 to allow the detecting rod to enter into the housing space 106 via the opening 108 so that the write protect is released.
In the background art of FIGS. 6 and 7, however, the upper and lower halves 102 and 103 are assembled together to form the cassette casing 101 with the manually operable switching member 107 being merely placed on a portion of the lower half 103 defining the housing space 106. Accordingly, it is likely to happen that the switching member 107 falls off the lower half 103 during the assembling of the upper and lower halves 102 and 103.
In order to eliminate the above-noted problem, another type of a disk cartridge has been proposed as disclosed in Japanese First Utility Model Publication (Jikkaisho) 62-110773, which allows the manually operable switching member to be mounted into the cassette casing from the outside after the upper and lower halves have been assembled together. FIGS. 8 and 9 show this type of the disk cartridge, wherein the same or like parts or members are designated by the same reference numerals as in FIGS. 6 and 7. FIG. 8 shows the state where the manually operable switching member 107 is mounted in the housing space 106, while, FIG. 9 shows the state where the switching member 107 is being inserted into the housing space 106. The upper half 102 of the cassette casing 101 is formed with a stepped opening 109 having a wider section 110. The wider section 110 works as an inlet for inserting the switching member 107. The switching member 107 has a pair of resilient leg portions 107a, 107a.
As shown in FIG. 9, when mounting the switching member 107 into the housing space 106, the switching member 107 is first inserted through the wider section 110 in an inclined posture with the leg portions 107a, 107a being also in an inclined posture. Accordingly, the mounting operations of the switching member 107 into the housing space 106 inevitably becomes bothersome and difficult, and further, deformation or breakage of the leg portions 107a of the switching member is likely to happen.